The proposed project aims to design and field two more waves of survey data collection in Mexico, extending and improving the Mexican Health and Aging Study (MHAS). This is a national, multi-purpose, community-based, longitudinal cohort study of adults aged 50 and older. The two new waves will be fielded in 2018 and 2021, completing a cycle of 20 years since the first wave was fielded in 2001. Funds are also sought to continue to archive, document, and disseminate for public use the new waves as well as the resulting integrated data base containing all six waves. Since its inception, MHAS aimed to create a longitudinal prospective study of Mexican aging, starting with a national sample (n=15,000), using study protocols and survey instruments that were highly comparable to the U.S. Health and Retirement Study. In addition, the study design sought to facilitate the examination of long term implications for health and aging of the massive Mexico-U.S. migration flows. Thus, the sample design included an over-sample in states of Mexico with historically high levels of migration to the United States. The new waves will replicate and improve these and other unique features of previous rounds. New emphasis areas will be: environmental health; life histories; health literacy; evaluation of losses and deaths in the panel. We will also continue an emphasis on the culture of multi-generational Mexico-U.S. migration and its consequences for aging; and the impact for older adults of structural changes in Mexico such as the health sector reform that started in 2003 and the economic recession of 2009. Our aims are: 1) To carry out Waves 5 and 6 retaining the original substance of MHAS and adding new content, following the survivors of Waves 1 through 4, and refreshing the sample in Wave 5 to yield again a representative cross section of the Mexican population aged 50 and over; and 2) To enhance data linkages, data distribution, dissemination, and outreach activities and to expand knowledge about and use of the data sets and products of the resulting six waves of the MHAS. We will continue the user-friendly web-based platforms and educational materials whose enhanced public access to the data and project documentation have stimulated cross-country and other studies. The analytical significance of the new MHAS data will be exceptional, producing a national longitudinal study of aging that span over twenty years, which is unique for a developing country. The data platform will enhance research on aging and related population changes: of physical and mental health, physical and cognitive functionality, environmental risks, health behaviors and health care use, family support, aging and the life course, wealth, income, labor and retirement, migration and old age, and mortality, in a developing country aging fast with limited institutional support for individuals in old age, and with close social and economic ties to the United States. The data will enable cross-period and cross-cohort analyses of health and aging, and will continue to be highly comparable with other similar studies in developed and developing countries, enhancing the study of aging and health with a cross-national perspective.